1. Technical Field
The present invention relates a concentration detection apparatus that detects the concentration of liquid toner that includes carrier liquid and toner. The invention further relates to an image formation apparatus.
2. Related Art
An example of methods for detecting the concentration of liquid with the use of a liquid carrying roller is disclosed in JP-A-2000-249653. The liquid carrying roller disclosed therein is made up of an eccentric disk unit and two sandwiching disk units. The diameter of one of the two sandwiching disk units is the same as that of the other. In addition, the diameter of each sandwiching disk unit is larger than that of the eccentric disk unit. The eccentric disk unit is sandwiched between the two sandwiching disk units. Liquid whose concentration is to be detected is filled into a circumferential recess formed in a step between the eccentric disk unit and the two sandwiching disk units to have a plurality of thicknesses different from each other according to the step. Then, on the basis of the output of an optical sensor for the plurality of thicknesses, the concentration of the liquid is detected.
However, the technique disclosed in JP-A-2000-249653 has a problem in that output sensitivity fluctuates depending on the transmittance of liquid whose concentration is to be measured.